1. Field of the Invention
The present invention relates to a cylinder block made of fiber-reinforced light alloy for an internal combustion engine and more particularly to a cylinder block having a cylinder barrel with its portion around a cylinder bore formed by a fiber-reinforced part and a cylinder block outer wall surrounding the cylinder barrel and defining therebetween a water jacket.
2. Description of the Prior Art
There has been conventionally known a light alloy-made cylinder block for use with an internal combustion engine, which is cast therein with a cylinder sleeve made of cast iron (see U.S. Pat. No. 3,561,104).
If it is desired to further reduce the weight of a cylinder block obtained in accordance with the above prior art, a possible measure may be to reinforce the part of the cylinder block around its cylinder bore by fibers instead of using the cast iron-made cylinder sleeve.
If in this case a so-called open deck type design is employed for the cylinder block which has its water jacket opened at the cylinder head end portion thereof due to the use of a light alloy matrix having a low Young's modulus, that portion of the cylinder barrel which is located adjacent the cylinder head joining surface of the barrel shows a tendency to be deformed and enlarged in bore diameter when said portion is subjected to combustion gas pressure. This may disadvantageously result in an increase in the amount of blowby gas and of oil consumption.
Further, if the fiber-reinforced part is formed to have a large thickness in the radial direction of the cylinder bore with a view to improving the strength while keeping such thickness uniform over the entire length of the cylinder bore, there also will be a deterioration in the heat radiation property of the fiber-reinforced part at its portion adjacent the cylinder head joining surface which may result in a high temperature in that portion during engine operation.
Moreover, in a cylinder block for a multi-cylinder type internal combustion engine, when fiber-reinforced parts for respective cylinders are formed independently from each other, the respective fiber-reinforced parts contribute very little to the rigidity of the whole cylinder block although they have a relatively high rigidity in themselves by reason of the reinforcing fibers contained therein.